Iberia-Azores Gravity Model (IAGRM) using multi-source gravity data

Abstract

A consistent high precision and high resolution gravity model in the north-east Atlantic off Iberia peninsula using multi-source gravity data, ship-borne and satellite derived gravity anomalies, is presented. A solution strategy based on least squares optimal interpolation was used to assimilate into a coherent gravity model, gravity data with different spectral and spatial resolutions. Satellite derived gravity anomalies from KMS02 model, with an error covariance of 25 mGal 2 , and marine data carefully edited and validated by bias crossover error adjustment, were used in this study. The observation error variance was determined from ship-borne track adjustment and assigned an independent value for each track determined from error variance propagation. Unbiased ship-borne gravity observations were assimilated into the satellite derived gravity KMS02 model by the least squares optimal interpolation algorithm (OI) with bias removed by applying a regional bias to all ship tracks (OI-b) and alternatively by constraining all ship tracks to KMS02 using bias and tilt (OI-t). External error of the model was determined by comparing with recent surveys and it was verified that OI-t approach improved the final gravity model to an accuracy of about 3 mGal. The effect of different merging approaches on geoid solution was also evaluated and it was verified that the merging process can contribute to improve the geoid accuracy up to 4 cm with the OI-t approach.

Significance of Northeast‐Trending Features in Canada Basin, Arctic Ocean

“…The APPL lineament does not have an equivalent lineation or anomaly in gravity or upward continued gravity maps (Figure ), suggesting it does not represent a significant density boundary. Gravity anomalies along the boundaries between transitional and oceanic crust of the hyperextended Iberian margin are also small, ∼10 mgal, (Dean et al, ) and essentially indiscernible (Catalao, ) suggesting that a gravity anomaly is not a required condition at these kinds of crustal changes. APPL does, however, project into the Canadian margin offshore of Prince Patrick Island where the gravity data show a major saddle and change in direction of the shelf‐edge paired positive‐negative anomaly (SEPA of Figure a).…”

Constraints on the structure of Maio Island (Cape Verde) by a three-dimensional gravity model: imaging partially exhumed magma chambers

“…Using the autocorrelation analysis of the data and calculating a suitable analytical covariance function (e.g. Catalão 2006), the usual formulae for least‐squares prediction (Moritz 1980b) provides us with a first estimation of the signal at this level of covariance and the corresponding prediction error matrix. A residual signal is obtained by subtracting the estimated signal from the observed data.…”

Mapping the geoid for Iberia and the Macaronesian Islands using multi-sensor gravity data and the GRACE geopotential model

“…Other gravimetric geoid solutions have been attempted by Fernandes et al (2000) for the Azores area and Arabelos et al (1999) for the Iberian coast, both using FFT techniques. Several other studies have considered, respectively, the effect of bathymetry on the estimation of the geoid , satellite altimetry data processing (Fernandes et al 2006), the adjustment and validation of marine gravity data (Catalão and Sevilla 2004), the merging of multi-source gravity data (Catalão 2006), and the effect of mass density on the estimation of the geoid (Catalão and Bos 2008).…”